He wants to..

Lately everytime my SO and I have sex he tells me he wants to cum in my mouth. I keep saying no because it honestly doesn't catch my attention, I'm willing to try it since he's tried new things for me during sex. Before I say yes though, I HAD to ask my girls on glow! Have you tried it? What did you do? Did you swallow it? I'm so confused on what to do if I agree to do it! Lol help?!